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Biomedical subjects

E Witt

Publications and source records attributed to E Witt.

At least 55 records · Page 3Linked to original sources
PubMed1992

Ultraviolet light-induced generation of vitamin E radicals and their recycling. A possible photosensitizing effect of vitamin E in skin.

Vitamin E (alpha-tocopherol) is the major lipid-soluble chain-breaking antioxidant of membranes. Its UV-absorbance spectrum (lambda max 295 nm) extends well into the solar spectrum. We hypothesize that in skin alpha-tocopherol may absorb solar UV light and generate tocopheroxyl radicals. Reduction of tocopheroxyl radicals by other antioxidants (e.g. ascorbate, thiols) will regenerate (recycle) vitamin E at the expense of their own depletion. Hence, vitamin E in skin may act in two conflicting manners upon solar illumination: in addition to its antioxidant function as a peroxyl radical scavenger, it may act as an endogenous photosensitizer, enhancing light-induced oxidative damage. To test this hypothesis, we have illuminated various systems (methanol-buffer dispersions, liposomes and skin homogenates) containing alpha-tocopherol or its homologue with a shorter 6-carbon side chain, chromanol-alpha-C6 with UV light closely matching solar UV light, in the presence or absence of endogenous or exogenous reductants. We found that: (i) alpha-tocopheroxyl (chromanoxyl) radicals are directly generated by solar UV light in model systems (methanol-water dispersions, liposomes) and in skin homogenates; (ii) reducing antioxidants (ascorbate, ascorbate+dihydrolipoic acid) can donate electrons to alpha-tocopheroxyl (chromanoxyl) radicals providing for vitamin E (chromanol-alpha-C6) recycling; (iii) recycling of UV-induced alpha-tocopheroxyl radicals depletes endogenous antioxidant pools (accelerates ascorbate oxidation); (iv) beta-carotene, a non-reducing antioxidant, is not active in alpha-tocopherol recycling, and its UV-dependent depletion is unaffected by vitamin E.

Animals↗
PubMed1991

[The long-term results in orthodontic closure of a gap in the anterior teeth--the functional status].

In a follow-up study, the functional and occlusal status of patients after orthodontic space closure of missing incisors is compared with those who were not orthodontically treated. The investigation involved a method of instrument registration of TMJ function. The findings show that occlusion of our former patients in various mandibular positions is slightly different from ideal occlusal concept and we found no increased functional risk in this kind of treatment. In cases with missing incisors, orthodontic space closure that avoids prosthetic procedures should be taken into consideration.

Adult↗
PubMed1991

[Periodontal and esthetic aspects of orthodontic frontal space closure--results of a long-term study].

In this study follow-up results of patients are presented, who have been treated in cases of missing incisors by orthodontic space closure. The statements of clinical examinations, casts, intra- and extraoral photographies, x-rays, periodontal examinations and questionnaires pointed out, that the abnormal position of the moved teeth do not interfere with the periodontal tissues. Should the occasion arise of correction by crowns or by grinding, the patients consider the abnormal positioned teeth as esthetical.

Adult↗
PubMed1991

[The potentials and limits of orthodontic treatment for adults].

Progress in orthognathic surgery as well as the special methods now available for proper setting of osteotomic segments, diagnostic aids and therapeutic possibilities of orthodontics have considerably strengthened the case today for giving adults a combined treatment. The treatment provides patients with the requisite sense of functional and aesthetic rehabilitation. Follow-up studies confirm the success of treatment combining therapy and surgery.

Adult↗
PubMed1991

[The functional findings before and after a combined orthodontic and oral surgical treatment of Angle class-III patients].

The functional status of 25 adults with severe Angle class III maxillofacial disorders is described by anamnestic data and results of clinical as well as electronic-instrumental functional analysis. The examination was done shortly before surgical correction and after completion of the postoperative orthodontic treatment, whereby a significant reduction of TMJ clicking and more frequent nasal breathing were observed. Postoperative results of the clinical examination are characterized by fewer patients with TMJ symptoms and with lateral deviation of the mandible during mouth opening. Additionally an improved range of mandibular movement was noted. The electronic-instrumental functional analysis shows no risk of displacement of the condyle associated with surgical orthodontic treatment. The horizontal inclination of the condylar guidance (condyle path inclination) increases significantly after surgery.

Activator Appliances↗
PubMed1991

[The wear-timing measuring device in orthodontics--cui bono? Reflections on the state-of-the-art in wear-timing measurement and compliance research in orthodontics].

The recent development of fully functioning timing devices has yielded a new impulse to scientific research on orthodontic compliance. In contrast, promises and risks of the practical application of timing devices have thus far largely gone unheeded. In this survey, possible benefits of this new device are considered along with a critical discussion of technical and sociopsychological issues of its practical application. Following a review of the current state of orthodontic timing technology, basic implications of the collection and utilization of this new type of data are outlined. Short- and long-term perspectives of objective measurement of compliance are presented in terms of optimized treatment devices, enhanced patient compliance and improved orthodontist-patient relations. An evaluation project on benefits and risks of orthodontic timing devices is being called for.

Electronics, Medical↗
PubMed1991

Subjective appraisal of orthodontic practices. An investigation into perceived practice characteristics associated with patient and parent treatment satisfaction.

Based on a comprehensive in-practice questionnaire survey among 254 school-age patients and their parents, the subjective perception and evaluation of orthodontic care was investigated. By means of refined statistical analysis, three types of practice showing significantly distinct image profiles were identified. Likewise, the set of discriminating variables was reduced and assigned to the fundamental concepts of 'interpersonal satisfaction' and 'perceived efficacy' which appeared to play a crucial part in the crystallization of both patients' and parents' contentedness with the treatment received. To take account of the interdependence of instrumental and social factors, a model of perceived practice similarity is suggested; its significance regarding treatment decisions and future research efforts is pointed out.

Adolescent↗
PubMed1991

The functional status of orthodontically treated prognathic patients.

In order to study the prevalence of mandibular dysfunction in orthodontically treated prognathic patients after retention, 60 randomly selected patients were examined clinically. The functional status of the patients was evaluated using the anamnestic, clinical dysfunction index, and the index for occlusal status introduced by Helkimo. Our patients showed a better functional status than the untreated prognathic patients, but one poorer than that of the general population. No difference, as demonstrated by indices, could be found between chin-cup and non chin-cup group, or between the conservatively treated and surgically treated prognathic patients without pre-orthodontic treatment.

Adolescent↗
PubMed1991

TMJ function with and without orthodontic treatment.

In order to evaluate the functional status of the stomatognathic system of former orthodontic patients, a review of current literature is given. In addition, a sample of orthodontically-treated subjects and a control group was investigated by means of clinical functional analysis. The figures found in the literature and the results of this study failed to reveal orthodontic treatment as a frequent cause of stomatognathic dysfunction symptoms. Instead, we found the functional status and occlusal parameters of our former orthodontic patients to be more harmonious than in the control group.

Adult↗
PubMed1990

[Initial attitudes to orthodontic treatment--the results of a practical and clinical questionnaire study (I)].

312 patients from one clinic and nine offices, between eight and 15 years of age treated with bionators, their parents and a control group were questioned on various aspects of their treatment. Findings regarding opinions about dentofacial appearance, initial motives and expectations are presented. Aesthetic motives proved preponderant by seeking treatment though the children's ability to verbally differentiate aesthetic concepts was poor. Above all, they expected visible treatment progress, absence of appliance-caused psychosomatic impairment and rather factual information than personal communication with the orthodontist.

Activator Appliances↗
PubMed1990

[Orthodontic treatment from the patients' and parents' viewpoint--the results of a practical and clinical questionnaire study (II)].

A questionnaire investigation enrolling more than 300 orthodontic patients and their parents was conducted into the subjective appraisal of treatment means and doctor-patient-interaction. The majority of the interviewees showed a positive respectively indifferent attitude toward their treatment. As patients grow older, their views become more differentiated and critical. Impaired speaking was mentioned most frequently; psychosocial disadvantages caused by appliance wear were suggested mostly by parents. In a minor part of patients, the orthodontist's behavior was not in line with their social-emotional needs and expectations. Slight failures of adherence with prescriptions were admitted for the daytime. Parental supervision appeared to be either energetic or formal yet superficial, or insufficient respectively in one third of our cases.

Attitude to Health↗
PubMed1990

Micro-electronic monitoring of functional appliance wear.

Measurement of actual bionator wear has so far been confined to a few studies involving only small samples. In this study a micro-electronic timing device was used in a greater number of patients (53 children) after the system proved to be reliable in a pretest involving 18 subjects. The patients were 9-14 years of age and had a timing device fitted in their bionators over a period of 3-6 months. The data were read from the memory chip at the regular treatment sessions every 3-4 weeks. There was evidence that the patients averaged 7.65 hours per day of wear, thus fulfilling only 50-60 per cent of the orthodontist's requirements. Further details and implications of the measurements are discussed.

Activator Appliances↗
PubMed1990

Reliability of patient reports on compliance.

The reliability of subjective estimates of patient appliance wear plays a critical role in scientific research on compliance just as in everyday orthodontic practice. This problem was subjected to scrutiny by means of the recently developed electronic timing device and psychological investigations. Over several months 53 patients between 9 and 14 years of age treated with bionators were followed. Included were objective measurement of wearing time, judgements on compliance by patients, parents, and orthodontists, and questioning about numerous treatment-related and personality variables. These data allowed an assessment of subjective reports. Asked to classify patients as 'good', 'average', or 'poor' co-operators, neither the orthodontists nor the patients in their self-ratings exceeded 43 per cent of hits. From a heuristic model of how misjudgements on compliance arise, indicators were derived to represent certain stages of cognition formation in the patient. A strong association was found between actual compliance and patient credibility, in that generally 'poor co-operators' grossly overstate their wearing time. Consequently, various patient characteristics and features of operator-patient interaction proved significantly correlated with both criteria. Among them, regularity of wear and duration of treatment are most influential. Moreover, patient credibility appeared to be a salient point of the reciprocal perceptions of treatment partners and their personalities. The reliability of patient statements also depends upon: (1) how detailed the operator's questions are; (2) whether he draws his own conclusions from the information received instead of leaving them to the patient. This evidence may lead to greater accuracy in gauging patient compliance.

Activator Appliances↗
PubMed1990

[The bionator with extraoral traction--the Wurzburg concept. 1].

In this publication the bionator with extraoral anterior traction is presented. The preparation of the bionator and the headgear fit is demonstrated. The indication for the use of the appliance combination is outlined. The results of a cephalometric study concerning the therapeutic effects are presented. The following changes are especially noteworthy: There is a reduction of the SNA-angle, a significant retrusion of the upper incisors occurs. The mesial drift of the upper 6-year molars is inhibited, a slight posterior rotation of the maxilla is observed. In patients who wore their appliances well, a protrusion of the lower incisors could not be observed.

Activator Appliances↗
PubMed1989

[The head-chin cap--a functional risk?].

The investigation presented here is concerned with the question whether the use of a chin cap by prognathic patients involves a functional risk to the masticatory system. By a comparison of two patient groups through use of the Helkimo Index no evidence for this could be found.

Dental Occlusion↗